diff options
Diffstat (limited to 'fs/yaffs2/yaffs_nameval.c')
| -rw-r--r-- | fs/yaffs2/yaffs_nameval.c | 208 |
1 files changed, 208 insertions, 0 deletions
diff --git a/fs/yaffs2/yaffs_nameval.c b/fs/yaffs2/yaffs_nameval.c new file mode 100644 index 000000000..a20a3e47c --- /dev/null +++ b/fs/yaffs2/yaffs_nameval.c @@ -0,0 +1,208 @@ +/* + * YAFFS: Yet Another Flash File System. A NAND-flash specific file system. + * + * Copyright (C) 2002-2011 Aleph One Ltd. + * for Toby Churchill Ltd and Brightstar Engineering + * + * Created by Charles Manning <charles@aleph1.co.uk> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +/* + * This simple implementation of a name-value store assumes a small number of +* values and fits into a small finite buffer. + * + * Each attribute is stored as a record: + * sizeof(int) bytes record size. + * yaffs_strnlen+1 bytes name null terminated. + * nbytes value. + * ---------- + * total size stored in record size + * + * This code has not been tested with unicode yet. + */ + +#include "yaffs_nameval.h" + +#include "yportenv.h" + +static int nval_find(const char *xb, int xb_size, const YCHAR *name, + int *exist_size) +{ + int pos = 0; + int size; + + memcpy(&size, xb, sizeof(int)); + while (size > 0 && (size < xb_size) && (pos + size < xb_size)) { + if (!yaffs_strncmp((YCHAR *) (xb + pos + sizeof(int)), + name, size)) { + if (exist_size) + *exist_size = size; + return pos; + } + pos += size; + if (pos < xb_size - sizeof(int)) + memcpy(&size, xb + pos, sizeof(int)); + else + size = 0; + } + if (exist_size) + *exist_size = 0; + return -ENODATA; +} + +static int nval_used(const char *xb, int xb_size) +{ + int pos = 0; + int size; + + memcpy(&size, xb + pos, sizeof(int)); + while (size > 0 && (size < xb_size) && (pos + size < xb_size)) { + pos += size; + if (pos < xb_size - sizeof(int)) + memcpy(&size, xb + pos, sizeof(int)); + else + size = 0; + } + return pos; +} + +int nval_del(char *xb, int xb_size, const YCHAR *name) +{ + int pos = nval_find(xb, xb_size, name, NULL); + int size; + + if (pos < 0 || pos >= xb_size) + return -ENODATA; + + /* Find size, shift rest over this record, + * then zero out the rest of buffer */ + memcpy(&size, xb + pos, sizeof(int)); + memcpy(xb + pos, xb + pos + size, xb_size - (pos + size)); + memset(xb + (xb_size - size), 0, size); + return 0; +} + +int nval_set(char *xb, int xb_size, const YCHAR *name, const char *buf, + int bsize, int flags) +{ + int pos; + int namelen = yaffs_strnlen(name, xb_size); + int reclen; + int size_exist = 0; + int space; + int start; + + pos = nval_find(xb, xb_size, name, &size_exist); + + if (flags & XATTR_CREATE && pos >= 0) + return -EEXIST; + if (flags & XATTR_REPLACE && pos < 0) + return -ENODATA; + + start = nval_used(xb, xb_size); + space = xb_size - start + size_exist; + + reclen = (sizeof(int) + namelen + 1 + bsize); + + if (reclen > space) + return -ENOSPC; + + if (pos >= 0) { + nval_del(xb, xb_size, name); + start = nval_used(xb, xb_size); + } + + pos = start; + + memcpy(xb + pos, &reclen, sizeof(int)); + pos += sizeof(int); + yaffs_strncpy((YCHAR *) (xb + pos), name, reclen); + pos += (namelen + 1); + memcpy(xb + pos, buf, bsize); + return 0; +} + +int nval_get(const char *xb, int xb_size, const YCHAR * name, char *buf, + int bsize) +{ + int pos = nval_find(xb, xb_size, name, NULL); + int size; + + if (pos >= 0 && pos < xb_size) { + + memcpy(&size, xb + pos, sizeof(int)); + pos += sizeof(int); /* advance past record length */ + size -= sizeof(int); + + /* Advance over name string */ + while (xb[pos] && size > 0 && pos < xb_size) { + pos++; + size--; + } + /*Advance over NUL */ + pos++; + size--; + + /* If bsize is zero then this is a size query. + * Return the size, but don't copy. + */ + if (!bsize) + return size; + + if (size <= bsize) { + memcpy(buf, xb + pos, size); + return size; + } + } + if (pos >= 0) + return -ERANGE; + + return -ENODATA; +} + +int nval_list(const char *xb, int xb_size, char *buf, int bsize) +{ + int pos = 0; + int size; + int name_len; + int ncopied = 0; + int filled = 0; + + memcpy(&size, xb + pos, sizeof(int)); + while (size > sizeof(int) && + size <= xb_size && + (pos + size) < xb_size && + !filled) { + pos += sizeof(int); + size -= sizeof(int); + name_len = yaffs_strnlen((YCHAR *) (xb + pos), size); + if (ncopied + name_len + 1 < bsize) { + memcpy(buf, xb + pos, name_len * sizeof(YCHAR)); + buf += name_len; + *buf = '\0'; + buf++; + if (sizeof(YCHAR) > 1) { + *buf = '\0'; + buf++; + } + ncopied += (name_len + 1); + } else { + filled = 1; + } + pos += size; + if (pos < xb_size - sizeof(int)) + memcpy(&size, xb + pos, sizeof(int)); + else + size = 0; + } + return ncopied; +} + +int nval_hasvalues(const char *xb, int xb_size) +{ + return nval_used(xb, xb_size) > 0; +} |